Role of the middle ear muscle apparatus in mechanisms of speech signal discrimination

A method of impedance reflexometry was used to examine 101 students with hearing impairment in order to clarify the interrelation between speech discrimination and the state of the middle ear muscles. Ability to discriminate speech signals depends to some extent on the functional state of intraaural muscles. Speech discrimination was greatly impaired in the absence of stapedial muscle acoustic reflex, in the presence of low thresholds of stimulation and in very small values of reflex amplitude increase. Discrimination was not impeded in positive AR, high values of relative thresholds and normal increase of reflex amplitude in response to speech signals with augmenting intensity

Photonic crystals of coated metallic spheres

It is shown that simple face-centered-cubic (fcc) structures of both metallic and coated metallic spheres are ideal candidates to achieve a tunable complete photonic bandgap (CPBG) for optical wavelengths using currently available experimental techniques. For coated microspheres with the coating width to plasma wavelength ratio $l_c/\lambda_p \leq 10$ and the coating and host refractive indices $n_c$ and $n_h$, respectively, between 1 and 1.47, one can always find a sphere radius $r_s$ such that the relative gap width $g_w$ (gap width to the midgap frequency ratio) is larger than 5% and, in some cases, $g_w$ can exceed 9%. Using different coatings and supporting liquids, the width and midgap frequency of a CPBG can be tuned considerably.Comment: 14 pages, plain latex, 3 ps figures, to appear in Europhys. Lett. For more info on this subject see http://www.amolf.nl/research/photonic_materials_theory/moroz/moroz.htm

A simple formula for the L-gap width of a face-centered-cubic photonic crystal

The width $\triangle_L$ of the first Bragg's scattering peak in the (111) direction of a face-centered-cubic lattice of air spheres can be well approximated by a simple formula which only involves the volume averaged $\epsilon$ and $\epsilon^2$ over the lattice unit cell, $\epsilon$ being the (position dependent) dielectric constant of the medium, and the effective dielectric constant $\epsilon_{eff}$ in the long-wavelength limit approximated by Maxwell-Garnett's formula. Apparently, our formula describes the asymptotic behaviour of the absolute gap width $\triangle_L$ for high dielectric contrast $\delta$ exactly. The standard deviation $\sigma$ steadily decreases well below 1% as $\delta$ increases. For example $\sigma< 0.1$ for the sphere filling fraction $f=0.2$ and $\delta\geq 20$. On the interval $\delta\in(1,100)$, our formula still approximates the absolute gap width $\triangle_L$ (the relative gap width $\triangle_L^r$) with a reasonable precision, namely with a standard deviation 3% (4.2%) for low filling fractions up to 6.5% (8%) for the close-packed case. Differences between the case of air spheres in a dielectric and dielectric spheres in air are briefly discussed.Comment: 13 pages, 4 figs., RevTex, two references added. For more info see http://www.amolf.nl/external/wwwlab/atoms/theory/index.htm

The 3-PPPS parallel robot with U-shape Base, a 6-DOF parallel robot with simple kinematics

International audienceOne of the main problems associated with the use of 6 DOF parallel robots remains the solving of their kinematic models. This is rarely possible to analytically solve their models thereby justifying the application of numerical methods. These methods are difficult to implement in an industrial controller and can cause solution bifurcations close to singularities resulting in following an unplanned trajectory. Recently, a 3-PPPS robot with U-shaped base was introduced where an analytical kinematic model can be derived. Previously, quaternion parameters were used to represent the orientation of the mobile platform. To allow for simpler model handling, this article introduces the use of Euler angles which have a physical meaning for the users. Compact writing of the direct and inverse kinematic model is thus obtained. Using algebraic and cylindrical decomposition for the workspace, this provides a simpler representation of the largest domain without singularity around the " home " configuration

Mathematical modeling of pipes production forecast based on polynomial regression analysis (PRA)

The paper analyzes some indicators of the production activity of Ukraine’s metallurgical plants, which are under the auspices of Ukrtruboprom association for May-August 2022. Mathematical modeling of pipe production process forecast based on polynomial regression analysis was performed. The presented mathematical models provide adequate results for predicted indicators of economic activity of enterprises selected for analysis. The Russian military operations’ negative impact on the hostilities’ conduct in Ukraine is shown

A superconvergent representation of the Gersten-Nitzan and Ford-Webber nonradiative rates

An alternative representation of the quasistatic nonradiative rates of Gersten and Nitzan [J. Chem. Phys. 1981, 75, 1139] and Ford and Weber [Phys. Rep. 1984, 113, 195] is derived for the respective parallel and perpendicular dipole orientations. Given the distance d of a dipole from a sphere surface of radius a, the representations comprise four elementary analytic functions and a modified multipole series taking into account residual multipole contributions. The analytic functions could be arranged hierarchically according to decreasing singularity at the short distance limit d ---> 0, ranging from d^{-3} over d^{-1} to ln (d/a). The alternative representations exhibit drastically improved convergence properties. On keeping mere residual dipole contribution of the modified multipole series, the representations agree with the converged rates on at least 99.9% for all distances, arbitrary particle sizes and emission wavelengths, and for a broad range of dielectric constants. The analytic terms of the representations reveal a complex distance dependence and could be used to interpolate between the familiar d^{-3} short-distance and d^{-6} long-distance behaviors with an unprecedented accuracy. Therefore, the representations could be especially useful for the qualitative and quantitative understanding of the distance behavior of nonradiative rates of fluorophores and semiconductor quantum dots involving nanometal surface energy transfer in the presence of metallic nanoparticles or nanoantennas. As a byproduct, a complete short-distance asymptotic of the quasistatic nonradiative rates is derived. The above results for the nonradiative rates translate straightforwardly to the so-called image enhancement factors Delta, which are of relevance for the surface-enhanced Raman scattering.Comment: 30 pages including 6 figure

On the equivalence of the Langevin and auxiliary field quantization methods for absorbing dielectrics

Recently two methods have been developed for the quantization of the electromagnetic field in general dispersing and absorbing linear dielectrics. The first is based upon the introduction of a quantum Langevin current in Maxwell's equations [T. Gruner and D.-G. Welsch, Phys. Rev. A 53, 1818 (1996); Ho Trung Dung, L. Kn\"{o}ll, and D.-G. Welsch, Phys. Rev. A 57, 3931 (1998); S. Scheel, L. Kn\"{o}ll, and D.-G. Welsch, Phys. Rev. A 58, 700 (1998)], whereas the second makes use of a set of auxiliary fields, followed by a canonical quantization procedure [A. Tip, Phys. Rev. A 57, 4818 (1998)]. We show that both approaches are equivalent.Comment: 7 pages, RevTeX, no figure

Reduction of sulfur and oxidized forms of nitrogen by bacteria of Desulfuromonas sp., isolated from Yavorivske Lake, under the influence of ferrum citrate

Technogenic reservoirs mainly contain several possible electron acceptors of anaerobic respiration, many of which are dangerous to the environment. The succession of their reduction (and thus detoxification) by sulfur reducing bacteria is not yet sufficiently studied. We investigated the influence of ferrum (III) citrate, present in the cultivation medium, on the reduction of sulfur, nitrate and nitrite ions by sulfur reducing bacteria Desulfuromonas acetoxidans IMV B-7384, Desulfuromonas sp. Yavor-5 and Desulfuromonas sp. Yavor-7, isolated from Yavorivske Lake. It was established that ferrum (III) citrate inhibits the biomass accumulation and hydrogen sulfide production by bacteria of Desulfuromonas sp. after simultaneous addition to the medium of 3.47 mM S0 and 1.74–10.41 mM ferrum (III) citrate, as compared with growth and hydrogen sulfide production by bacteria in the medium with only sulfur. In the medium with the same initial content (3.47 mM) S0 and ferrum (III) citrate bacteria produced ferrum (II) ions at concentrations 3.5–3.9 times higher than that of hydrogen sulfide. Ferrum (III) citrate inhibits the biomass accumulation, the nitrate or nitrite ions reduction and the ammonium ions production by bacteria of Desulfuromonas sp. after simultaneous addition to the medium of 3.47&nbsp;mM NaNO3 or NaNO2 and 1.74–10.41 mM ferrum (III) citrate. In the medium with the same initial content (3.47 mM) NaNO3 and ferrum (III) citrate, bacteria produced ammonium ions at concentrations in 1.1 times higher than that of ferrum (II) ions. In the medium with the same initial content (3.47 mM) NaNO2 and ferrum (III) citrate, bacteria reduced 1.5–1.6 times more ferrum (III) than nitrite ions with production of ferrum (II) ions at concentrations 1.7 times higher than that of ammonium ions. The process of nitrate reduction carried out by bacteria of Desulfuromonas genus was less sensitive to the negative influence of ferrum (III) citrate, compared to the process of nitrite ions reduction. When the reduction of nitrate ions by bacteria in the presence of 1.74–10.41 mM ferrum (III) citrate decreased by 1.4–2.2 times, then the reduction of nitrite ions decreased by 1.8–3.2 times compared to their reduction in media with only NaNO3 or NaNO2, respectively. Although the reduction of ferrum (III) by cells in media with 3.47 mM S0, NaNO3 or NaNO2 and 1.74–10.41 mM ferrum (III) citrate decreased by 1.6–2.7, 1.6–2.7 and 1.1–2.2 times, respectively, compared to the reduction in medium with only ferrum (III) citrate, the investigated strains of bacteria were resistant to high concentrations of trivalent ferrum compounds and can therefore can be used in technologies of complex purification of environments polluted by heavy metal and nitrogen compounds

Rashba effect in 2D mesoscopic systems with transverse magnetic field

We present semiclassical and quantum mechanical results for the effects of a strong magnetic field in Quantum Wires in the presence of Rashba Spin Orbit coupling. Analytical and numerical results show how the perturbation acts in the presence of a transverse magnetic field in the ballistic regime and we assume a strong reduction of the backward scattering interaction which could have some consequences for the Tomonaga-Luttinger transport. We analyze the spin texture due to the action of Spin Orbit coupling and magnetic field often referring to the semiclassical solutions that magnify the singular spin polarization: results are obtained for free electrons in a twodimensional electron gas and for electrons in a Quantum Wire. We propose the systems as possible devices for the spin filtering at various regimes.Comment: 12 pages, 12 figures, to appear in Phys. Rev.

Spin-orbit coupling in interacting quasi-one-dimensional electron systems

We present a new model for the study of spin-orbit coupling in interacting quasi-one-dimensional systems and solve it exactly to find the spectral properties of such systems. We show that the combination of spin-orbit coupling and electron-electron interactions results in: the replacement of separate spin and charge excitations with two new kinds of bosonic mixed-spin-charge excitation, and a characteristic modification of the spectral function and single-particle density of states. Our results show how manipulation of the spin-orbit coupling, with external electric fields, can be used for the experimental determination of microscopic interaction parameters in quantum wires.Comment: 5 pages including 4 figures; RevTeX; to appear in Phys.Rev.Let